Different from a railway vehicle running on rails, a vehicle in a new transportation system in which a vehicle body runs being carried by rubber tires driven under rotation, is normally provided with steering guide wheels making contact with a guide rail laid along the track, for turning the rubber tires serving as running wheels, along a predetermined track, that is, the vehicle runs being mechanically steered.
As the guide rail, there have been presented the so-called side guide type and center guide type guide rails.
For example, as to the side guide type, Japanese Patent Laid-Open No. 59-11955 discloses a bogie for a guide rail type vehicle, having guide wheels which are attached to distal ends of guide beams projected from the opposite sides of a vehicle body and which are made to contact with guide rails so as to steer running wheels in association with the motion of the guide beams in leftward and rightward directions.
Explanation will be made of the structure of the bogie which is shown in FIGS. 2 and 3 in the above-mentioned document with reference to FIGS. 13 and 14 which show a portion of the bogie corresponding to one of axles.
An output power shaft of an electric motor which is not shown is coupled to a differential gear unit 012 carried by an axle body 010 and having an output power shaft which drives left and right running wheels 014, 014 of rubber tire type through the intermediary of an axle shaft and universal joints which are incorporated in the axle body 010 and which are not shown.
The running wheels 014 are supported respectively to opposite end parts of the axle body 010 by means of king pins 016 so as to be horizontally swingable, and the axle body 010 is bolted to a part of a mounting eye 020 provided to the lower surface of a frame 018, just inside of the king pins 016.
Further, suspension air springs 024 for vertical suspension are provided between the frame 018 and a bed frame 022 of the bogie 019.
Further, as shown in FIG. 14, upper rods 028 are attached between the frame 018 and brackets 026 which are secured to the bed frame 022, and lower rods 032 are attached between the brackets 026 attached to the bed frame 022 and brackets 030 which are secured to the axle body 010. Further, as shown in FIG. 13, a horizontal rod 036 is attached between a bracket 034 which is secured to the bed frame 022 and the frame 018. The upper rods 028, the lower rods 032 and the horizontal rod 036 serve as support rods in a suspension system.
Further, in a steering mechanism, guide wheels 042, 042 respectively attached to left and right end parts of a guide beam 040 which is extended left and right of the vehicle are rotated along left and right guide rails which are not shown, so as to be guided. Further, the displacement of the guide wheels 042, left and right of the vehicle, is transmitted to a guide wheel unit 046 composed of the guide beams 040 and the like, being guided by two rotating arms 044, 044, and then is transmitted to a steering arm 052 through the intermediary of steering rods 048, 050 so as to turn the left and right running wheels 014, 014 through the intermediary of a tie rod 054. Thus, the left and right wheels 014, 014 are steered in synchronization with each other, being guided along the left and right guide rails.
Further, Japanese Patent Laid-Open No. 09-315297 also discloses a bogie for a guide rail type vehicle having guide wheels which are attached to distal end parts of guide beams projected from the opposite sides of a vehicle body and which are made into contact with guide rails so as to steer the vehicle body in association with the left and right motions of the guide beams.
Further, as the center guide type, Japanese Patent Laid-Open No. 2002-019603 discloses the configuration that guide wheels are made into contact with a guide rail laid on a road surface so as to guide running of an automatic running vehicle when tires of the automatic running vehicle are laterally displaced exceeding an allowable limit of automatic steering.
However, the structure of the bogie of the side guide type track vehicle, as disclosed in the Japanese Patent Laid-Open No. 59-11955, requires extra components such as the guide beams 040 which are mounted at their both ends with the guide wheels 042, 042 and are extended left and right, and the two left and right arms 044 for pivotally supporting the guide beam 040, and further, the these components are heavy, resulting in an increase in the weight, and as well, are also bulky, resulting in a problem of occupation of a wide space. Further, during running, the guide wheels 042 make into contact with the guide rails, intermittently or continuously, with impacts, resulting in severe abrasion, and accordingly, the guide wheels 042, 042, the guide beam 040, the arms 044, 044 and the like require workings for periodical maintenance, and replacement of components. Further, since they are bulky and heavy, the maintainability thereof are problematic.
Thus, it has been desired to improve the structure of the bogie so as to be lightweight with excellent maintainability.
Further, the center guide type as disclosed in the Japanese Patent Laid-Open No. 2002-019603 only has a limited space between the lower part of the vehicle and the running surface, in which required mechanisms including guide wheels should be accommodated.
Thus, three has been desired the structure of the bogie that required mechanisms including the guide wheels can be accommodated in a narrow space between the lower part of the vehicle and the guide rails, incorporating a novel guide wheel mechanism which is lightweight with excellent maintainability.
Further, in addition, there have known as the prior art that guide wheels make contact with guide rails laid along a track so as to mechanically steer the vehicle on running, U.S. Pat. No. 6,520,303 (Patent Document 3), U.S. Pat. No. 6,364,215 (Patent Document 4) and WO00/53480 (Patent Document 5).